There are 1 questions in this calculation: for each question, the 1 derivative of y is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ (x + ay){\frac{1}{(x + y)}}^{2}\ with\ respect\ to\ y：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{x}{(x + y)^{2}} + \frac{ay}{(x + y)^{2}}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{x}{(x + y)^{2}} + \frac{ay}{(x + y)^{2}}\right)}{dy}\\=&(\frac{-2(0 + 1)}{(x + y)^{3}})x + 0 + (\frac{-2(0 + 1)}{(x + y)^{3}})ay + \frac{a}{(x + y)^{2}}\\=&\frac{-2x}{(x + y)^{3}} - \frac{2ay}{(x + y)^{3}} + \frac{a}{(x + y)^{2}}\\ \end{split}\end{equation} \]

Your problem has not been solved here? Please take a look at the  hot problems ！